来自天蓝色链霉菌的IV型限制性内切酶ScoMcrA的结晶及初步X射线分析，该酶可切割Dcm甲基化DNA和硫代磷酸化DNA。
Crystallization and preliminary X-ray analysis of the type IV restriction endonuclease ScoMcrA from Streptomyces coelicolor, which cleaves both Dcm-methylated DNA and phosphorothioated DNA.
作者信息
Liu Guang, Zhang Zhenyi, Zhao Gong, Deng Zixin, Wu Geng, He Xinyi
机构信息
State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, People's Republic of China.
出版信息
Acta Crystallogr F Struct Biol Commun. 2015 Jan 1;71(Pt 1):57-60. doi: 10.1107/S2053230X14025801.
ScoMcrA is a type IV modification-dependent restriction endonuclease found in the model strain Streptomyces coelicolor. Unlike type I, II and III restriction endonucleases, which cleave unmodified DNA, type IV restriction endonucleases cleave modified DNA, including methylated, hydroxymethylated, glucosyl-hydroxymethylated and phosphorothioated DNA. ScoMcrA targets both Dcm-methylated DNA and phosphorothioated DNA, and makes double-strand breaks 16-28 nt away from the modified nucleotides or the phosphorothioate links. However, the mechanism by which ScoMcrA recognizes these two entirely different types of modification remains unclear. In this study, the ScoMcrA protein was overexpressed, purified and crystallized. The crystals diffracted to 3.35 Å resolution and belonged to space group P2(1)2(1)2(1). The unit-cell parameters were determined to be a=130.19, b=139.36, c=281.01 Å, α=β=γ=90°. These results will facilitate the detailed structural analysis of ScoMcrA and further elucidation of its biochemical mechanism.
ScoMcrA是在模式菌株天蓝色链霉菌中发现的一种IV型依赖修饰的限制性内切酶。与切割未修饰DNA的I型、II型和III型限制性内切酶不同，IV型限制性内切酶切割修饰的DNA，包括甲基化、羟甲基化、葡萄糖基 - 羟甲基化和硫代磷酸化的DNA。ScoMcrA靶向Dcm甲基化的DNA和硫代磷酸化的DNA，并在距离修饰核苷酸或硫代磷酸酯连接16 - 28 nt处产生双链断裂。然而，ScoMcrA识别这两种完全不同类型修饰的机制仍不清楚。在本研究中，ScoMcrA蛋白被过量表达、纯化并结晶。晶体衍射分辨率达到3.35 Å，属于空间群P2(1)2(1)2(1)。晶胞参数确定为a = 130.19，b = 139.36，c = 281.01 Å，α = β = γ = 90°。这些结果将有助于对ScoMcrA进行详细的结构分析，并进一步阐明其生化机制。
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